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Dr. Mou Leong Tan
Geography Section, School of Humanities, Universiti Sains Malaysia

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0 Remote Sensing
0 Hydrologic and Water Resource Modeling and Simulation
0 SWAT model
0 climate change

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Journal article
Published: 17 July 2021 in Environmental Research
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This study aims to analyze the pollution characteristics and sources of heavy metal elements for the first time in the Zhundong mining area in Xinjiang using the linear regression model. Additionaly, the health risks with their probability and infleuencing factors on different groups of people's were also evaluated using Monte Carlo (MC) simulation approach. The results shows that 89.28% of Hg was from coal combustion, 40.28% of Pb was from transportation, and 19.54% of As was from atmospheric dust. The main source of Cu and Cr was coal dust, Hg has the greatest impact on potential ecological risks. which accounted for 60.2% and 81.46% of the Cu and Cr content in soil, respectively. The all samples taken from Pb have been Extremely polluted (100%). 93.3% samples taken from As have been Extremely polluted. The overall potential ecological risk was moderate. Adults experienced higher non-carcinogenic risks of heavy metals from their diets than children. Interestingly, body weight was the main factor affecting the adult's health risks. This research provides more comprehensive information for better soil management, soil remediation, and soil pollution control in the Xinjiang mining areas.

ACS Style

Haiwei Zhang; Fei Zhang; Jia Song; Mou Leong Tan; Hsiang-Te Kung; Verner Carl Johnson. Pollutant source, ecological and human health risks assessment of heavy metals in soils from coal mining areas in Xinjiang, China. Environmental Research 2021, 202, 111702 .

AMA Style

Haiwei Zhang, Fei Zhang, Jia Song, Mou Leong Tan, Hsiang-Te Kung, Verner Carl Johnson. Pollutant source, ecological and human health risks assessment of heavy metals in soils from coal mining areas in Xinjiang, China. Environmental Research. 2021; 202 ():111702.

Chicago/Turabian Style

Haiwei Zhang; Fei Zhang; Jia Song; Mou Leong Tan; Hsiang-Te Kung; Verner Carl Johnson. 2021. "Pollutant source, ecological and human health risks assessment of heavy metals in soils from coal mining areas in Xinjiang, China." Environmental Research 202, no. : 111702.

Review
Published: 08 July 2021 in Science of The Total Environment
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Alternative climate products, such as gauge-based gridded data, ground-based weather radar, satellite precipitation and climate reanalysis products, are being increasingly applied for hydrological modelling. This review aims to summarize the studies that have evaluated alternative climate products within Soil and Water Assessment Tool (SWAT) applications and to propose future research directions, primarily for modelers who wish to study limited gauge, ungauged or transnational river basins. A total of 126 articles have been identified since 2004, the majority of which have been published within the last five years. About 58% of the studies were conducted in Asia, mostly in China and India, while another 14% were reported for United States studies. CFSR and TRMM are the most popular applied products in SWAT modelling, followed by PERSIANN, CMADS, APHRODITE, CHIRPS and NEXRAD. Generally, the performance of climate products is region-dependent; e.g., CFSR typically performs well in the United States and South America, but performs more poorly for Asia, Africa and mountainous basin conditions, as compared to other products. In contrast, the CMADS, TRMM, APRHODITE and NEXRAD have shown the strongest capability for supporting SWAT modelling in these regions. However, most of the evaluated products contain only precipitation input; therefore, merging reliable precipitation with CFSR-temperature is recommended for hydro-climatic modelling. Future research directions include: (1) examination of optimal combinations; e.g. CHIRPS-precipitation and CFSR-temperature, for simulating streamflow in different types of river basins; (2) development of a standardized validation scheme which incorporates the commonly accepted products, statistical approaches and temperature variables; (3) further evaluation of existing climate data products to accurately capture extreme events, pattern and indices as well as WGEN statistics; (4) improvement of climate data in terms of averaging approach, bias correction and additional factors or indices integration; and (5) bias correction of CMIP6 climate projections using the optimal climate data combinations.

ACS Style

Mou Leong Tan; Philip W. Gassman; Ju Liang; James M. Haywood. A review of alternative climate products for SWAT modelling: Sources, assessment and future directions. Science of The Total Environment 2021, 795, 148915 .

AMA Style

Mou Leong Tan, Philip W. Gassman, Ju Liang, James M. Haywood. A review of alternative climate products for SWAT modelling: Sources, assessment and future directions. Science of The Total Environment. 2021; 795 ():148915.

Chicago/Turabian Style

Mou Leong Tan; Philip W. Gassman; Ju Liang; James M. Haywood. 2021. "A review of alternative climate products for SWAT modelling: Sources, assessment and future directions." Science of The Total Environment 795, no. : 148915.

Journal article
Published: 21 June 2021 in Agriculture
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Climate change is a global problem since many countries worldwide are becoming increasingly vulnerable to natural disasters. Numerous climate models in various studies project a decline in agricultural productivity that will mainly be due to excessive heat in tropical and subtropical regions, especially in Southeast Asia. As a Southeast Asian country, Malaysia is no exception to this problem. Hence, the present study aimed to examine the impact of climate change on rice yields in Malaysia. A panel data approach was adopted using data from 1987 to 2017 on eight granary areas in Peninsular Malaysia. The main objectives were to assess the impact of climate variables (i.e., minimum and maximum temperature and precipitation) on rice yield and the variance of the impact during the main season and off-season. Our regression results indicate that precipitation was not statistically significant in all model specifications for both the main and off-season. While the maximum temperature was found to be negatively associated with yield during the off-season, the minimum temperature showed a positive effect in both cropping seasons. We used the HadGEM3-GC31 N512 resolution model based on the high-emission Shared Socioeconomic Pathways 8.5 scenario (SSPs-8.5) from the High-Resolution Model Intercomparison Project (HighResMIP) of the Coupled Model Intercomparison Project Phase 6 (CMIP6) to project future climate change in 2030 and 2040. The projected results indicate that rice yield would show a more positive trend by 2040 when compared to the previous decade, ranging from −0.02 to 19.85% during the main season and −2.77 to 7.41% during the off-season. Although rice yield is likely to increase in certain areas, other areas are projected to experience negative effects. Hence, adaptation at the farm level remains crucial, specifically during the off-season, since climate change could widen the gaps in rice yields between cropping seasons and among granary areas.

ACS Style

Boon Tan; Pei Fam; R. Firdaus; Mou Tan; Mahinda Gunaratne. Impact of Climate Change on Rice Yield in Malaysia: A Panel Data Analysis. Agriculture 2021, 11, 569 .

AMA Style

Boon Tan, Pei Fam, R. Firdaus, Mou Tan, Mahinda Gunaratne. Impact of Climate Change on Rice Yield in Malaysia: A Panel Data Analysis. Agriculture. 2021; 11 (6):569.

Chicago/Turabian Style

Boon Tan; Pei Fam; R. Firdaus; Mou Tan; Mahinda Gunaratne. 2021. "Impact of Climate Change on Rice Yield in Malaysia: A Panel Data Analysis." Agriculture 11, no. 6: 569.

Journal article
Published: 25 May 2021 in Journal of Hydrology: Regional Studies
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The Muda River Basin (MRB), Malaysia. This study proposed a framework to improve the European Space Agency Climate Change Initiative Land Cover (ESA CCI LC) products through the integration with the Annual Oil Palm Dataset (AOPD). The improved land use land cover (LULC) maps were then used to produce five LULC scenarios as input maps into the Soil and Water Assessment Tool (SWAT) model for analyzing the impact of LULC changes on water balance in the MRB. The improved LULC maps have good performance in representing rubber and oil palm, with an overall accuracy up to 81 %. In addition, SWAT simulated monthly streamflow well for the MRB, with the highest R2 and NSE values of 0.84 and 0.86, respectively. During the 2001–2016 period, the MRB experienced an expansion of oil palm from 7.10%–17.36 %, a reduction of rubber from 34.93 % to 26.38 % and a slight decrease in forest from 54.23%–52.80 %. The urban expansion scenario showed significant increment in surface runoff, while the reforestation scenario helped to reduce surface runoff, while increase lateral flow and groundwater. Oil palm expansion led to a higher reduction in lateral flow and groundwater than rubber trees due to the higher soil water absorption rate. The proposed framework can be duplicated and applied in other tropical basins, particularly in Indonesia and Malaysia.

ACS Style

Mou Leong Tan; Yi Lin Tew; Kwok Pan Chun; Narimah Samat; Shazlyn Milleana Shaharudin; Mohd Amirul Mahamud; Fredolin T. Tangang. Improvement of the ESA CCI Land cover maps for water balance analysis in tropical regions: A case study in the Muda River Basin, Malaysia. Journal of Hydrology: Regional Studies 2021, 36, 100837 .

AMA Style

Mou Leong Tan, Yi Lin Tew, Kwok Pan Chun, Narimah Samat, Shazlyn Milleana Shaharudin, Mohd Amirul Mahamud, Fredolin T. Tangang. Improvement of the ESA CCI Land cover maps for water balance analysis in tropical regions: A case study in the Muda River Basin, Malaysia. Journal of Hydrology: Regional Studies. 2021; 36 ():100837.

Chicago/Turabian Style

Mou Leong Tan; Yi Lin Tew; Kwok Pan Chun; Narimah Samat; Shazlyn Milleana Shaharudin; Mohd Amirul Mahamud; Fredolin T. Tangang. 2021. "Improvement of the ESA CCI Land cover maps for water balance analysis in tropical regions: A case study in the Muda River Basin, Malaysia." Journal of Hydrology: Regional Studies 36, no. : 100837.

Journal article
Published: 24 May 2021 in Water
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This study introduces a hydro-climatic extremes assessment framework that combines the latest climate simulations from the Coupled Model Intercomparison Project Phase 6 (CMIP6) HighResMIP with the Soil and Water Assessment (SWAT) model, and examines the influence of the different climate model resolutions. Sixty-six hydrological and environmental flow indicators from the Indicators of Hydrologic Alteration (IHA) were computed to assess future extreme flows in the Kelantan River Basin (KRB), Malaysia, which is particularly vulnerable to flooding. Results show that the annual precipitation, streamflow, maximum and minimum temperatures are projected to increase by 6.9%, 9.9%, 0.8 °C and 0.9 °C, respectively, by the 2021–2050 period relative to the 1985–2014 baseline. Monthly precipitation and streamflow are projected to increase especially for the Southwest Monsoon (June–September) and the early phase of the Northeast Monsoon (December) periods. The magnitudes of the 1-, 3-, 7-, 30- and 90-day minima flows are projected to increase by 7.2% to 8.2% and the maxima flows by 10.4% to 28.4%, respectively. Lastly, changes in future hydro-climatic extremes are frequently quite different between the high-resolution and low-resolution models, e.g., the high-resolution models projected an increase of 11.8% in mean monthly flow in November-December-January compared to 3.2% for the low-resolution models.

ACS Style

Mou Tan; Ju Liang; Narimah Samat; Ngai Chan; James Haywood; Kevin Hodges. Hydrological Extremes and Responses to Climate Change in the Kelantan River Basin, Malaysia, Based on the CMIP6 HighResMIP Experiments. Water 2021, 13, 1472 .

AMA Style

Mou Tan, Ju Liang, Narimah Samat, Ngai Chan, James Haywood, Kevin Hodges. Hydrological Extremes and Responses to Climate Change in the Kelantan River Basin, Malaysia, Based on the CMIP6 HighResMIP Experiments. Water. 2021; 13 (11):1472.

Chicago/Turabian Style

Mou Tan; Ju Liang; Narimah Samat; Ngai Chan; James Haywood; Kevin Hodges. 2021. "Hydrological Extremes and Responses to Climate Change in the Kelantan River Basin, Malaysia, Based on the CMIP6 HighResMIP Experiments." Water 13, no. 11: 1472.

Research article
Published: 01 April 2021 in Complexity
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Prediction of daily rainfall is important for flood forecasting, reservoir operation, and many other hydrological applications. The artificial intelligence (AI) algorithm is generally used for stochastic forecasting rainfall which is not capable to simulate unseen extreme rainfall events which become common due to climate change. A new model is developed in this study for prediction of daily rainfall for different lead times based on sea level pressure (SLP) which is physically related to rainfall on land and thus able to predict unseen rainfall events. Daily rainfall of east coast of Peninsular Malaysia (PM) was predicted using SLP data over the climate domain. Five advanced AI algorithms such as extreme learning machine (ELM), Bayesian regularized neural networks (BRNNs), Bayesian additive regression trees (BART), extreme gradient boosting (xgBoost), and hybrid neural fuzzy inference system (HNFIS) were used considering the complex relationship of rainfall with sea level pressure. Principle components of SLP domain correlated with daily rainfall were used as predictors. The results revealed that the efficacy of AI models is predicting daily rainfall one day before. The relative performance of the models revealed the higher performance of BRNN with normalized root mean square error (NRMSE) of 0.678 compared with HNFIS (NRMSE = 0.708), BART (NRMSE = 0.784), xgBoost (NRMSE = 0.803), and ELM (NRMSE = 0.915). Visual inspection of predicted rainfall during model validation using density-scatter plot and other novel ways of visual comparison revealed the ability of BRNN to predict daily rainfall one day before reliably.

ACS Style

Lu Ye; Saadya Fahad Jabbar; Musaddak M. Abdul Zahra; Mou Leong Tan. Bayesian Regularized Neural Network Model Development for Predicting Daily Rainfall from Sea Level Pressure Data: Investigation on Solving Complex Hydrology Problem. Complexity 2021, 2021, 1 -14.

AMA Style

Lu Ye, Saadya Fahad Jabbar, Musaddak M. Abdul Zahra, Mou Leong Tan. Bayesian Regularized Neural Network Model Development for Predicting Daily Rainfall from Sea Level Pressure Data: Investigation on Solving Complex Hydrology Problem. Complexity. 2021; 2021 ():1-14.

Chicago/Turabian Style

Lu Ye; Saadya Fahad Jabbar; Musaddak M. Abdul Zahra; Mou Leong Tan. 2021. "Bayesian Regularized Neural Network Model Development for Predicting Daily Rainfall from Sea Level Pressure Data: Investigation on Solving Complex Hydrology Problem." Complexity 2021, no. : 1-14.

Journal article
Published: 16 March 2021 in Sustainability
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Flooding is a frequent, naturally recurring phenomenon worldwide that can become disastrous if not addressed accordingly. This paper aims to evaluate the impacts of land use change and climate change on flooding in the Segamat River Basin, Johor, Malaysia, with 1D–2D hydrodynamic river modeling, using InfoWorks Integrated Catchment Modeling (ICM). The study involved the development of flood maps for four different scenarios: (1) future land use in 2030; (2) the impacts of climate change; (3) three mitigation strategies comprising detention ponds, rainwater harvesting systems (RWHSs), and permeable pavers; and (4) a combination of these three mitigation strategies. The obtained results show increases in the flood peaks under both the land use change and climate change scenarios. With the anticipated increase in development activities within the vicinity up to 2030, the overall impact of urbanization on the extent of flooding would be rather moderate, as the upper and middle parts of the basin would still be dominated by forests and agricultural activities (approximately 81.13%). In contrast, the potential flood-inundated area is expected to increase from 12.25% to 16.64% under storms of 10-, 50-, 100-, and 1000-year average recurrence intervals (ARI). Interestingly, the simulation results suggest that only the detention pond mitigation strategy has a considerable impact on reducing floods, while the other two mitigation strategies have less flood reduction advantages for this agricultural-based rural basin located in a tropical region.

ACS Style

Yuk Liew; Safari Mat Desa; Md. Noh; Mou Tan; Nor Zakaria; Chun Chang. Assessing the Effectiveness of Mitigation Strategies for Flood Risk Reduction in the Segamat River Basin, Malaysia. Sustainability 2021, 13, 3286 .

AMA Style

Yuk Liew, Safari Mat Desa, Md. Noh, Mou Tan, Nor Zakaria, Chun Chang. Assessing the Effectiveness of Mitigation Strategies for Flood Risk Reduction in the Segamat River Basin, Malaysia. Sustainability. 2021; 13 (6):3286.

Chicago/Turabian Style

Yuk Liew; Safari Mat Desa; Md. Noh; Mou Tan; Nor Zakaria; Chun Chang. 2021. "Assessing the Effectiveness of Mitigation Strategies for Flood Risk Reduction in the Segamat River Basin, Malaysia." Sustainability 13, no. 6: 3286.

Journal article
Published: 04 January 2021 in Sustainability
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A few studies on outdoor human thermal comfort (HTC) have been conducted in the tropical region in a hot and humid climate; however, there is a paucity of discussions on how exactly different spatial settings influence HTC. Thus, this paper aims to examine how land use land cover (LULC) affects HTC on the basis of the simulation of Predicted Mean Vote (PMV) and Physiologically Equivalent Temperature (PET) indices via ENVI-met and Rayman. The results reveal that people living in the urban area have a higher tendency to experience strong heat stress (25% of the areas with PMV ranging from 3.4 to 3.9 and 2% of the areas, where PMV reached 4.1), followed by the rural area (43% of the areas with PMV ranging from 2.1 to 2.4), and the suburban area (more than 50% of the areas with PMV values less than 2.4). Surprisingly, a concrete LULC in the suburb area exhibits a higher air temperature than an asphalt surface at 4 p.m., due to the large area of high albedo that increases the reflection of solar radiation, subsequently contributing to warming up the airmass. Similarly, sandy, and loamy LULC tend to emit more heat during nighttime, while the heat is absorbed slowly during daytime, and it is then slowly released during nighttime after 6 p.m. Spatial settings that promote heat stress in the urban area are mainly contributed by an LULC of asphalt, concrete, sandy, and loamy areas. Meanwhile, people in the suburban and rural areas are less likely to experience heat stress, due to agricultural plantations and lowland forest that provide shade, except for the barren lands-loamy areas. The result also indicates that tree-covered areas near the river in the suburban area afforded the best thermal experience with PMV of 2.1 and PET of 30.7. From the LULC comparison, it is pivotal to consider tree species (canopy density), surface material (albedo), sky-view factor, wind direction, and speed toward designing a more comfortable and sustainable environment.

ACS Style

Lee Yeo; Gabriel Ling; Mou Tan; Pau Leng. Interrelationships between Land Use Land Cover (LULC) and Human Thermal Comfort (HTC): A Comparative Analysis of Different Spatial Settings. Sustainability 2021, 13, 382 .

AMA Style

Lee Yeo, Gabriel Ling, Mou Tan, Pau Leng. Interrelationships between Land Use Land Cover (LULC) and Human Thermal Comfort (HTC): A Comparative Analysis of Different Spatial Settings. Sustainability. 2021; 13 (1):382.

Chicago/Turabian Style

Lee Yeo; Gabriel Ling; Mou Tan; Pau Leng. 2021. "Interrelationships between Land Use Land Cover (LULC) and Human Thermal Comfort (HTC): A Comparative Analysis of Different Spatial Settings." Sustainability 13, no. 1: 382.

Journal article
Published: 23 November 2020 in Water
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Identification of reliable alternative climate input data for hydrological modelling is important to manage water resources and reduce water-related hazards in ungauged or poorly gauged basins. This study aims to evaluate the capability of the National Centers for Environmental Prediction Climate Forecast System Reanalysis (NCEP-CFSR) and China Meteorological Assimilation Driving Dataset for the Soil and Water Assessment Tool (SWAT) model (CMADS) for simulating streamflow in the Muda River Basin (MRB), Malaysia. The capability was evaluated in two perspectives: (1) the climate aspect—validation of precipitation, maximum and minimum temperatures from 2008 to 2014; and (2) the hydrology aspect—comparison of the accuracy of SWAT modelling by the gauge station, NCEP-CFSR and CMADS products. The results show that CMADS had a better performance than NCEP-CFSR in the climate aspect, especially for the temperature data and daily precipitation detection capability. For the hydrological aspect, the gauge station had a “very good” performance in a monthly streamflow simulation, followed by CMADS and NCEP-CFSR. In detail, CMADS showed an acceptable performance in SWAT modelling, but some improvements such as bias correction and further SWAT calibration are needed. In contrast, NCEP-CFRS had an unacceptable performance in validation as it dramatically overestimated the low flows of MRB and contains time lag in peak flows estimation.

ACS Style

Dandan Zhang; Mou Leong Tan; Sharifah Rohayah Sheikh Dawood; Narimah Samat; Chun Kiat Chang; Ranjan Roy; Yi Lin Tew; Mohd Amirul Mahamud. Comparison of NCEP-CFSR and CMADS for Hydrological Modelling Using SWAT in the Muda River Basin, Malaysia. Water 2020, 12, 3288 .

AMA Style

Dandan Zhang, Mou Leong Tan, Sharifah Rohayah Sheikh Dawood, Narimah Samat, Chun Kiat Chang, Ranjan Roy, Yi Lin Tew, Mohd Amirul Mahamud. Comparison of NCEP-CFSR and CMADS for Hydrological Modelling Using SWAT in the Muda River Basin, Malaysia. Water. 2020; 12 (11):3288.

Chicago/Turabian Style

Dandan Zhang; Mou Leong Tan; Sharifah Rohayah Sheikh Dawood; Narimah Samat; Chun Kiat Chang; Ranjan Roy; Yi Lin Tew; Mohd Amirul Mahamud. 2020. "Comparison of NCEP-CFSR and CMADS for Hydrological Modelling Using SWAT in the Muda River Basin, Malaysia." Water 12, no. 11: 3288.

Journal article
Published: 04 November 2020 in Hydrological Sciences Journal
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ACS Style

Xiaogang Li; Suzhen Huang; Ruimin He; Guoqing Wang; Mou Leong Tan; Xiaoying Yang; Zheng Zheng. Impact of temporal rainfall resolution on daily streamflow simulations in a large-sized river basin. Hydrological Sciences Journal 2020, 65, 2630 -2645.

AMA Style

Xiaogang Li, Suzhen Huang, Ruimin He, Guoqing Wang, Mou Leong Tan, Xiaoying Yang, Zheng Zheng. Impact of temporal rainfall resolution on daily streamflow simulations in a large-sized river basin. Hydrological Sciences Journal. 2020; 65 (15):2630-2645.

Chicago/Turabian Style

Xiaogang Li; Suzhen Huang; Ruimin He; Guoqing Wang; Mou Leong Tan; Xiaoying Yang; Zheng Zheng. 2020. "Impact of temporal rainfall resolution on daily streamflow simulations in a large-sized river basin." Hydrological Sciences Journal 65, no. 15: 2630-2645.

Research article
Published: 06 October 2020 in International Journal of Climatology
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Understanding the changes in temperature extremes is important for managing and coping with the risks associated with regional climate change. However, the climatological characteristics of temperature extremes and their variabilities is still not adequately studies in Malaysia. This study evaluates the spatial and temporal variations of temperature extremes over Malaysia for the period 1985‐2018. This study includes four phases: (1) collection, quality control and homogeneity analysis of temperature data; (2) general (TXmean, TNmean, TMmean and DTR), warm (TXx, TNx, TX90p and TN90p) and cool (TXn, TNn, TX10p and TN10p) temperature extreme indices calculations; (3) trend analysis of temperature extremes using the Mann‐Kendall and Sens’s slope test; and (4) analyses of correlations between temperature extremes and El Niño‐Southern Oscillation (ENSO). The results indicate a warming of surface temperature across Malaysia, particularly in Peninsular Malaysia. In general, TXmean, TNmean and TMmean increased significantly at 5% significance level by 0.12°C/decade, 0.27°C/decade and 0.17°C/decade, respectively. A significant decreasing trend in DTR by 0.12°C/decade is seen, which is related to the higher increasing rate of TNmean. All of the warm extreme indices, TXx, TNx, TX90p and TN90p presents significant increasing trends by 0.19°C/decade, 0.28°C/decade, 2.86%/decade and 3.08%/decade, respectively. For the cool extreme indices, TX10p and TN10p decreased significantly by 0.95%/decade and 3.18%/decade, respectively, though the trend in TXn by 0.11oC/decade is not statistically significant. The only cool index presenting a significant increasing trend is TNn by 0.44°C/decade, indicating a reduction of cool nights. Besides that, major cities in the northern and western parts of Peninsular Malaysia generally exhibit a higher warming trend compared to rural and highland area. These are possibly related to the intensified urban heat island effect under the rapid urbanization. This study also found that the ENSO affected warm extreme indices much stronger than cool extreme indices in Malaysia.

ACS Style

Mou Leong Tan; Liew Juneng; Fredolin T. Tangang; Jing Xiang Chung; R. B. Radin Firdaus. Changes in temperature extremes and their relationship with ENSO in Malaysia from 1985 to 2018. International Journal of Climatology 2020, 41, 1 .

AMA Style

Mou Leong Tan, Liew Juneng, Fredolin T. Tangang, Jing Xiang Chung, R. B. Radin Firdaus. Changes in temperature extremes and their relationship with ENSO in Malaysia from 1985 to 2018. International Journal of Climatology. 2020; 41 (S1):1.

Chicago/Turabian Style

Mou Leong Tan; Liew Juneng; Fredolin T. Tangang; Jing Xiang Chung; R. B. Radin Firdaus. 2020. "Changes in temperature extremes and their relationship with ENSO in Malaysia from 1985 to 2018." International Journal of Climatology 41, no. S1: 1.

Journal article
Published: 05 October 2020 in Land
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Drastic growth of urban populations has caused expansion of peri-urban areas—the transitional zone between a city and its hinterland. Although urbanisation may bring economic opportunities and improve infrastructure in an area, uncontrolled urban expansion towards peri-urban areas will negatively impact the environment and the community living within the area. Malaysia, for example, has become one of the most urbanised countries in East Asia. However, cities in Malaysia are relatively small and less densely populated compared with other cities in East Asia. This indicates that urban expansion has been sprawling towards peri-urban areas, and not being controlled and properly managed. To ensure urban expansions occur sustainably, urban growth boundary (UGB) can potentially be used as a mechanism to contain and limit urban expansion, and allow urban growth to be planned to achieve sustainable development. A scientific approach is essential to determine an UGB that allows future growth to be predicted and taken into consideration. Potentially, urban spatial models have been widely used to plan and predict future urban expansions. George Town Conurbation, the second largest urban conurbation in Malaysia, has been chosen as the study area in this study. This study aims to demonstrate the application of a GIS-Cellular Automata model, known as FutureSim, which was developed to simulate land cover changes and generate a designated UGB for this area. The model was developed based on the transition rule derived from land cover changes, from 2010 to 2018, and then used to predict future land cover changes under two different planning scenarios—compact growth and urban sprawl scenarios. With the accuracy of the model exceeding 74%, FutureSim was used to predict land cover change until 2030. The model can potentially be used to assist planners and policymakers to make decisions on the allocation of sustainable land use and planning for rapidly developing regions.

ACS Style

Narimah Samat; Mohd Amirul Mahamud; Mou Leong Tan; Mohammad Javad Maghsoodi Tilaki; Yi Lin Tew. Modelling Land Cover Changes in Peri-Urban Areas: A Case Study of George Town Conurbation, Malaysia. Land 2020, 9, 373 .

AMA Style

Narimah Samat, Mohd Amirul Mahamud, Mou Leong Tan, Mohammad Javad Maghsoodi Tilaki, Yi Lin Tew. Modelling Land Cover Changes in Peri-Urban Areas: A Case Study of George Town Conurbation, Malaysia. Land. 2020; 9 (10):373.

Chicago/Turabian Style

Narimah Samat; Mohd Amirul Mahamud; Mou Leong Tan; Mohammad Javad Maghsoodi Tilaki; Yi Lin Tew. 2020. "Modelling Land Cover Changes in Peri-Urban Areas: A Case Study of George Town Conurbation, Malaysia." Land 9, no. 10: 373.

Journal article
Published: 27 August 2020 in Science of The Total Environment
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Water quality monitoring is a pillar in water resource management, but it can be resource intensive, especially for developing countries with limited resources. As such, Water Quality Indices (WQI) are developed to summarise general water quality, but efforts to assess the utility, flexibility, and practicality of WQI have been limited. In this study, we introduced an additional step to the traditional WQI development framework by introducing an adjusted form of WQI (WQIADJUSTED) to handle missing values, and capitalise on the remaining available information for the development of a WQI. A Sub-WQI was also developed to address local water quality conditions. WQI results (weighted and non-weighted) developed using different parameter optimisation methods, namely Multivariate Linear Regression and Principal Component Analysis were compared. To build upon the current framework, a new procedure was developed to assess the adequacy of WQI based on the sensitivity analysis of parameters and uncertainties associated with each parameter's missing values distribution. The number of observations needed for the development of a robust WQI was optimised with respect to user-defined acceptable change in WQI, based on Monte Carlo probabilistic simulation. The Johor River Basin (JRB), Malaysia is used as a case-study for the application of this new framework. The JRB serves as an important resource for Johor, one of the most populous state in Malaysia, and Singapore, a country south of Johor. WQIMLR performed better in explaining the general water quality than WQIPCA for weighted water quality parameters. Optimisation of sampling frequency revealed that around 130 samples will be required if a 2% change in WQI can be tolerated. The results (specific to the JRB) also revealed that total coliform is the most sensitivity parameter to missing values, and the distribution of sensitive parameters are similar for both WQINON-ADJUSTED and WQIADJUSTED.

ACS Style

Hui Ying Pak; C. Joon Chuah; Mou Leong Tan; Ee Ling Yong; Shane A. Snyder. A framework for assessing the adequacy of Water Quality Index – Quantifying parameter sensitivity and uncertainties in missing values distribution. Science of The Total Environment 2020, 751, 141982 .

AMA Style

Hui Ying Pak, C. Joon Chuah, Mou Leong Tan, Ee Ling Yong, Shane A. Snyder. A framework for assessing the adequacy of Water Quality Index – Quantifying parameter sensitivity and uncertainties in missing values distribution. Science of The Total Environment. 2020; 751 ():141982.

Chicago/Turabian Style

Hui Ying Pak; C. Joon Chuah; Mou Leong Tan; Ee Ling Yong; Shane A. Snyder. 2020. "A framework for assessing the adequacy of Water Quality Index – Quantifying parameter sensitivity and uncertainties in missing values distribution." Science of The Total Environment 751, no. : 141982.

Journal article
Published: 25 July 2020 in Atmospheric Research
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A holistic framework was introduced to project the potential hydro-meteorological droughts of the Kelantan River basin, Malaysia. The framework integrates the multi-model high-resolution climate projections of the Coordinated Regional Climate Downscaling Experiment – Southeast Asia (CORDEX-SEA) and the widely applied Soil and Water Assessment Tool (SWAT) model. The quantile mapping approach was used to reduce the biases in the CORDEX-SEA projections before applying into SWAT. The SWAT-simulated standardized streamflow index (SSI) was validated with observed data to check the capability of SWAT in drought estimation. The result indicated that SWAT was able to reproduce the historical 1982, 1987 and 1997–1998 droughts and simulate SSI from one to twelve-month scales well, with the NSE and R2 values of 0.74–0.79 and 0.76–0.80, respectively. Overall, the annual precipitation, maximum and minimum temperatures are projected to change from −8.19 to 13.11% (−13.35 to 10.10%), 0.45 to 2.41 °C (0.43 to 3.99 °C) and 0.73 to 2.98 °C (0.70 to 4.69 °C), respectively, by the end of the 21st century under the RCP4.5 (RCP8.5) scenario. This would cause the future annual streamflow to vary from −10.37 to 31.09% and − 19.87 to 13.24% under RCP4.5 and RCP8.5, respectively, with the reductions are mainly found in the north-western region of the basin. Monthly precipitation and streamflow would be likely to decrease in January and February and increase in September. Robust evidence shows that the meteorological drought duration is likely to become longer in the 2081–2100 period under RCP4.5. Meanwhile, there is not enough evidence to claim that hydrological drought will become more significant in the near future.

ACS Style

Mou Leong Tan; Liew Juneng; Fredolin T. Tangang; Narimah Samat; Ngai Weng Chan; Zulkifli Yusop; Sheau Tieh Ngai. SouthEast Asia HydrO-meteorological droughT (SEA-HOT) framework: A case study in the Kelantan River Basin, Malaysia. Atmospheric Research 2020, 246, 105155 .

AMA Style

Mou Leong Tan, Liew Juneng, Fredolin T. Tangang, Narimah Samat, Ngai Weng Chan, Zulkifli Yusop, Sheau Tieh Ngai. SouthEast Asia HydrO-meteorological droughT (SEA-HOT) framework: A case study in the Kelantan River Basin, Malaysia. Atmospheric Research. 2020; 246 ():105155.

Chicago/Turabian Style

Mou Leong Tan; Liew Juneng; Fredolin T. Tangang; Narimah Samat; Ngai Weng Chan; Zulkifli Yusop; Sheau Tieh Ngai. 2020. "SouthEast Asia HydrO-meteorological droughT (SEA-HOT) framework: A case study in the Kelantan River Basin, Malaysia." Atmospheric Research 246, no. : 105155.

Article
Published: 29 June 2020 in Environment, Development and Sustainability
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Existing adaptation planning processes are inadequate to address the impacts of flooding. The goal of the study is to design adaptation pathways for enhancing livelihood resilience of flood-affected households in Bangladesh—one of the most flood-vulnerable countries in the world. We developed adaptation pathways by using three sequential steps: (1) assessing livelihood resilience by constructing resilience indices; (2) determining adaptation options by employing principal component analysis (PCA) of resilience indicators; and (3) designing pathways of selected adaptation options by conducting key informant interviews (KIIs), and participatory workshops. Livelihood resilience was assessed based on an established framework that builds on 18 indicators representing three capacities (absorptive, adaptive and transformative) and six dimensions: social, institutional, economic, ecological, physical, and political. Using a structured questionnaire survey, we collected data from 360 households of 18 villages of 9 sub-districts in Bangladesh. Results revealed that about one-third of total households had capacities to reduce flood shocks and stresses and improve livelihood opportunities. Following a resilience assessment, we conducted PCA for determining adaptation options, namely learning, infrastructure, and governance. Through KIIs and stakeholder engagement workshops, pathways of selected adaptation options were designed. The adaptation pathways entail short-, medium-, and long-term adaptation options, which contribute to maintaining persistence, leading to the transition, and facilitating transformation. Essential issues of implementation of adaptation pathways were determined. Critical policy implications around strengthening governance, promoting economy, and managing technologies were outlined.

ACS Style

Ranjan Roy; Animesh K. Gain; Margot A. Hurlbert; Narimah Samat; Mou Leong Tan; Ngai Weng Chan. Designing adaptation pathways for flood-affected households in Bangladesh. Environment, Development and Sustainability 2020, 23, 5386 -5410.

AMA Style

Ranjan Roy, Animesh K. Gain, Margot A. Hurlbert, Narimah Samat, Mou Leong Tan, Ngai Weng Chan. Designing adaptation pathways for flood-affected households in Bangladesh. Environment, Development and Sustainability. 2020; 23 (4):5386-5410.

Chicago/Turabian Style

Ranjan Roy; Animesh K. Gain; Margot A. Hurlbert; Narimah Samat; Mou Leong Tan; Ngai Weng Chan. 2020. "Designing adaptation pathways for flood-affected households in Bangladesh." Environment, Development and Sustainability 23, no. 4: 5386-5410.

Original paper
Published: 29 June 2020 in Environmental Geochemistry and Health
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Monitoring the groundwater chemical composition and identifying the presence of pollutants is an integral part of any comprehensive groundwater management strategy. The present study was conducted in a part of West Tripura, northeast India, to investigate the presence and sources of trace metals in groundwater and the risk to human health due to direct ingestion of groundwater. Samples were collected from 68 locations twice a year from 2016 to 2018. Mixed Ca–Mg–HCO3, Ca–Cl and Ca–Mg–Cl were the main groundwater types. Hydrogeochemical methods showed groundwater mineralization due to (1) carbonate dissolution, (2) silicate weathering, (3) cation exchange processes and (4) anthropogenic sources. Occurrence of faecal coliforms increased in groundwater after monsoons. Nitrate and microbial contamination from wastewater infiltration were apparent. Iron, manganese, lead, cadmium and arsenic were above the drinking water limits prescribed by the Bureau of Indian Standards. Water quality index indicated 1.5% had poor, 8.7% had marginal, 16.2% had fair, 66.2% had good and 7.4% had excellent water quality. Correlation and principal component analysis reiterated the sources of major ions and trace metals identified from hydrogeochemical methods. Human exposure assessment suggests health risk due to high iron in groundwater. The presence of unsafe levels of trace metals in groundwater requires proper treatment measures before domestic use.

ACS Style

K. Brindha; Rajib Paul; Julien Walter; Mou Leong Tan; Mahesh Kumar Singh. Trace metals contamination in groundwater and implications on human health: comprehensive assessment using hydrogeochemical and geostatistical methods. Environmental Geochemistry and Health 2020, 42, 3819 -3839.

AMA Style

K. Brindha, Rajib Paul, Julien Walter, Mou Leong Tan, Mahesh Kumar Singh. Trace metals contamination in groundwater and implications on human health: comprehensive assessment using hydrogeochemical and geostatistical methods. Environmental Geochemistry and Health. 2020; 42 (11):3819-3839.

Chicago/Turabian Style

K. Brindha; Rajib Paul; Julien Walter; Mou Leong Tan; Mahesh Kumar Singh. 2020. "Trace metals contamination in groundwater and implications on human health: comprehensive assessment using hydrogeochemical and geostatistical methods." Environmental Geochemistry and Health 42, no. 11: 3819-3839.

Review
Published: 16 June 2020 in Advances in Water Resources
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Hydro-climatic extremes, such as droughts and floods, have most likely increased due to climatic change and could lead to severe impacts on socio-economic, structural and environmental sectors. With nearly 4000 publications, the Soil and Water Assessment Tool (SWAT) is clearly one of the most extensively used ecohydrological models worldwide. The model has been widely used for projecting the impacts of future hydro-climatic changes, but application for extreme streamflow conditions is still rarely reported. To date, SWAT application reviews have focused on compilations of SWAT studies for specific or relatively new applications such as eco-hydrological modelling, ecosystem services, sub-daily simulations, and pesticide fate and transport simulations. However, no existing SWAT review studies have focused on simulation of hydro-climatic extremes. Therefore, this research aims to bridge this gap by compiling and reviewing the findings of studies reporting SWAT hydro-climatic extremes including highlighting the performance and future research needs. A total of 111 articles have been identified since 1999; most of these studies were conducted in the United States and China. These articles can be divided into extreme flow assessments, drought studies, flood studies, drought and flood studies, SWAT coupling with other models, and SWAT improvements. Most of the extreme performance assessment studies reported “satisfactory” performance, with a particular emphasis on peak flow comparisons. Future research needs regarding this topic include: (1) a unified SWAT extreme performance assessment framework; (2) SWAT improvements that result in improved replication of peak and low flows; (3) reliability assessment of global and satellite products for SWAT extreme simulations; (4) bias correction of CMIP6 and regional climate projections; (5) comparison of SWAT+ and SWAT for extreme flow simulations in different types of basins; (6) development of an extreme flow module within an overall SWAT modelling system; and (7) integration of artificial intelligence within SWAT modelling.

ACS Style

Mou Leong Tan; Philip W. Gassman; Xiaoying Yang; James Haywood. A review of SWAT applications, performance and future needs for simulation of hydro-climatic extremes. Advances in Water Resources 2020, 143, 103662 .

AMA Style

Mou Leong Tan, Philip W. Gassman, Xiaoying Yang, James Haywood. A review of SWAT applications, performance and future needs for simulation of hydro-climatic extremes. Advances in Water Resources. 2020; 143 ():103662.

Chicago/Turabian Style

Mou Leong Tan; Philip W. Gassman; Xiaoying Yang; James Haywood. 2020. "A review of SWAT applications, performance and future needs for simulation of hydro-climatic extremes." Advances in Water Resources 143, no. : 103662.

Journal article
Published: 23 May 2020 in Atmospheric Research
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The Ru River Basin is facing severe water security challenges such as frequent occurrence of extreme events and serious nutrient enrichment of its water bodies. In simulating daily streamflow, monthly total nitrogen (TN) loads, and monthly total phosphorous (TP) loads of the basin, the SWAT (Soil and Water Assessment Tool) model utilizing hourly rainfall inputs was found to perform considerably better than the model utilizing daily rainfall inputs. For climate change impact assessment, the hourly weather generator AWE-GEN was calibrated based on historical hourly rainfall records from 1970 to 1999 in the basin. Evaluation of its performance have indicated that the AWE-GEN could reasonably characterize the main features of monthly, daily, and hourly rainfall in the basin. The outputs of eight GCMs under a total of four climate change scenarios were then downscaled with the AWE-GEN to produce synthetic future hourly rainfall series to drive the hourly rainfall SWAT model for climate change impact assessment. The ensemble of SWAT simulation results have suggested that future streamflow, TN loads and TP loads were all likely to increase in the flood season in the Ru River Basin. Since the Ru River has already been afflicted with nutrient enrichment issues, the projected increase in nutrient loads due to climate change necessitates the enforcement of additional nutrient abatement measures to offset the adverse impacts imposed by climate change.

ACS Style

Xiaoying Yang; Ruimin He; Jinyin Ye; Mou Leong Tan; Xiyan Ji; Lit Tan; Guoqing Wang. Integrating an hourly weather generator with an hourly rainfall SWAT model for climate change impact assessment in the Ru River Basin, China. Atmospheric Research 2020, 244, 105062 .

AMA Style

Xiaoying Yang, Ruimin He, Jinyin Ye, Mou Leong Tan, Xiyan Ji, Lit Tan, Guoqing Wang. Integrating an hourly weather generator with an hourly rainfall SWAT model for climate change impact assessment in the Ru River Basin, China. Atmospheric Research. 2020; 244 ():105062.

Chicago/Turabian Style

Xiaoying Yang; Ruimin He; Jinyin Ye; Mou Leong Tan; Xiyan Ji; Lit Tan; Guoqing Wang. 2020. "Integrating an hourly weather generator with an hourly rainfall SWAT model for climate change impact assessment in the Ru River Basin, China." Atmospheric Research 244, no. : 105062.

Journal article
Published: 01 April 2020 in Bulletin of Electrical Engineering and Informatics
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Rainfall data are the most significant values in hydrology and climatology modelling. However, the datasets are prone to missing values due to various issues. This study aspires to impute the rainfall missing values by using various imputation method such as Replace by Mean, Nearest Neighbor, Random Forest, Non-linear Interactive Partial Least-Square (NIPALS) and Markov Chain Monte Carlo (MCMC). Daily rainfall datasets from 48 rainfall stations across east-coast Peninsular Malaysia were used in this study. The dataset were then fed into Multiple Linear Regression (MLR) model. The performance of abovementioned methods were evaluated using Root Mean Square Method (RMSE), Mean Absolute Error (MAE) and Nash-Sutcliffe Efficiency Coefficient (CE). The experimental results showed that RF coupled with MLR (RF-MLR) approach was attained as more fitting for satisfying the missing data in east-coast Peninsular Malaysia.

ACS Style

Siti Mariana Che Mat Nor; Shazlyn Milleana Shaharudin; Shuhaida Ismail; Nurul Hila Zainuddin; Mou Leong Tan. A comparative study of different imputation methods for daily rainfall data in east-coast Peninsular Malaysia. Bulletin of Electrical Engineering and Informatics 2020, 9, 635–643 .

AMA Style

Siti Mariana Che Mat Nor, Shazlyn Milleana Shaharudin, Shuhaida Ismail, Nurul Hila Zainuddin, Mou Leong Tan. A comparative study of different imputation methods for daily rainfall data in east-coast Peninsular Malaysia. Bulletin of Electrical Engineering and Informatics. 2020; 9 (2):635–643.

Chicago/Turabian Style

Siti Mariana Che Mat Nor; Shazlyn Milleana Shaharudin; Shuhaida Ismail; Nurul Hila Zainuddin; Mou Leong Tan. 2020. "A comparative study of different imputation methods for daily rainfall data in east-coast Peninsular Malaysia." Bulletin of Electrical Engineering and Informatics 9, no. 2: 635–643.

Journal article
Published: 24 March 2020 in Remote Sensing
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Owing to their advantages of wide coverage and high spatiotemporal resolution, satellite precipitation products (SPPs) have been increasingly used as surrogates for traditional ground observations. In this study, we have evaluated the accuracy of the latest five GPM IMERG V6 and TRMM 3B42 V7 precipitation products across the monthly, daily, and hourly scale in the hilly Shuaishui River Basin in East-Central China. For evaluation, a total of four continuous and three categorical metrics have been calculated based on SPP estimates and historical rainfall records at 13 stations over a period of 9 years from 2009 to 2017. One-way analysis of variance (ANOVA) and multiple posterior comparison tests are used to assess the significance of the difference in SPP rainfall estimates. Our evaluation results have revealed a wide-ranging performance among the SPPs in estimating rainfall at different time scales. Firstly, two post-time SPPs (IMERG_F and 3B42) perform considerably better in estimating monthly rainfall. Secondly, with IMERG_F performing the best, the GPM products generally produce better daily rainfall estimates than the TRMM products. Thirdly, with their correlation coefficients all falling below 0.6, neither GPM nor TRMM products could estimate hourly rainfall satisfactorily. In addition, topography tends to impose similar impact on the performance of SPPs across different time scales, with more estimation deviations at high altitude. In general, the post-time IMERG_F product may be considered as a reliable data source of monthly or daily rainfall in the study region. Effective bias-correction algorithms incorporating ground rainfall observations, however, are needed to further improve the hourly rainfall estimates of the SPPs to ensure the validity of their usage in real-world applications.

ACS Style

Xiaoying Yang; Yang Lu; Mou Leong Tan; Xiaogang Li; Guoqing Wang; Ruimin He. Nine-Year Systematic Evaluation of the GPM and TRMM Precipitation Products in the Shuaishui River Basin in East-Central China. Remote Sensing 2020, 12, 1042 .

AMA Style

Xiaoying Yang, Yang Lu, Mou Leong Tan, Xiaogang Li, Guoqing Wang, Ruimin He. Nine-Year Systematic Evaluation of the GPM and TRMM Precipitation Products in the Shuaishui River Basin in East-Central China. Remote Sensing. 2020; 12 (6):1042.

Chicago/Turabian Style

Xiaoying Yang; Yang Lu; Mou Leong Tan; Xiaogang Li; Guoqing Wang; Ruimin He. 2020. "Nine-Year Systematic Evaluation of the GPM and TRMM Precipitation Products in the Shuaishui River Basin in East-Central China." Remote Sensing 12, no. 6: 1042.